The type of _Hyla vilarsi_ is a gravid female having a snout-vent length of 62.7 mm. The diameter of the tympanum is 4.8 mm, 73.8 percent of the diameter of the eye. The dorsal roofing bones of the skull are moderately exostosed, and the lateral edges of the frontoparietals are distinctly elevated. The skin on the dorsum is smooth. Melin (1941:42) described the coloration of the holotype as follows: "Above uniform reddish brown; upper eyelids and sides of head darkish brown; below the rostral edge a narrow dark band, continuing as a broader light-edged one through the eye and tympanum towards the base of the forelimb and then farther on continuing along the sides as a line of black spots; sides of upper jaw whitish with traces of dark cross bars (one distinct under the eye); sides of body darkish with black spots and marble, often on a whitish ground; thighs, tibiae, and tarsi each with two broad light-edged, dark cross bars on a brownish ground (less distinct on thighs); sides of thighs finely mottled with brown; beneath whitish with small, sparse spots along jaw, on the chest and sides." We examined the type on 17 February 1969, at which time the specimen was somewhat desiccated, especially the hands and feet. The coloration remains much the same as described by Melin, except that he failed to note the presence of four elongate spots on the back. The status of the names _Osteocephalus planiceps_ Cope and _Hyla vilarsi_ Melin was confused by Cochran and Goin (1970:322), who assigned these names to the synonymy of _O. leprieurii_. Bokermann (1966:64) placed _Hyla vilarsi_ in the synonymy of _Osteocephalus taurinus_ without justification. The type specimens of both _planiceps_ and _vilarsi_ have moderately exostosed dermal roofing bones and distinct cranial ridges. The type of _planiceps_ has moderately large tubercles on the dorsum, and the type of _vilarsi_ has spots on the throat, chest, and flanks and longitudinal markings on the back. All of these features are characteristic of _taurinus_ and not of _leprieurii_, which lacks exostosis and cranial ridges and has transverse markings on the back, no spots on the throat, chest, and flanks, and in males has small dorsal tubercles.